[vtkusers] Closed vtkPolyLine to binary image

Mon Jul 12 10:16:49 EDT 2010

I ran your example and the only difference between stripper->GetOutput()
and my outline were the normals.

My code is as follows: (your code but with a readin of my circle
and given image dimensions etc.)

The vtk File can be found here:
http://www.nabla.org/circle.vtk

The resulting image is black only.

#include <vtkSmartPointer.h>
#include <vtkPolyData.h>
#include <vtkImageData.h>
#include <vtkSphereSource.h>
#include <vtkMetaImageWriter.h>
#include <vtkPolyDataToImageStencil.h>
#include <vtkImageStencil.h>
#include <vtkPointData.h>
#include <vtkCutter.h>
#include <vtkPlane.h>
#include <vtkStripper.h>
#include <vtkLinearExtrusionFilter.h>
#include <vtkXMLPolyDataWriter.h>
#include <vtkPolyDataReader.h>

int main(int argc, char **argv)
{
vtkSmartPointer< vtkPolyDataReader > polyreader=vtkSmartPointer<
vtkPolyDataReader >::New();
	polyreader->SetFileName("circle.vtk");
	polyreader->Update();

	vtkSmartPointer<vtkPolyData> circle = polyreader->GetOutput();

	// prepare the binary image's voxel grid
	vtkSmartPointer<vtkImageData> whiteImage =
	  vtkSmartPointer<vtkImageData>::New();
	double spacing[3]; // desired volume spacing
	spacing[0] = 2.0;
	spacing[1] = 2.0;
	spacing[2] = 2.0;
	whiteImage->SetSpacing(spacing);

	// compute dimensions
	int dim[3]={256,256,1};
	whiteImage->SetDimensions(dim);
	whiteImage->SetExtent(0, dim[0] - 1, 0, dim[1] - 1, 0, dim[2] - 1);
	double origin[3]={0,0,0};
	whiteImage->SetOrigin(origin);
	whiteImage->SetScalarTypeToUnsignedChar();
	whiteImage->AllocateScalars();
	// fill the image with foreground voxels:
	unsigned char inval = 255;
	unsigned char outval = 0;
	vtkIdType count = whiteImage->GetNumberOfPoints();
	for (vtkIdType i = 0; i < count; ++i)
	{
		whiteImage->GetPointData()->GetScalars()->SetTuple1(i, inval);
	}

	// sweep polygonal data (this is the important thing with contours!)
	vtkSmartPointer<vtkLinearExtrusionFilter> extruder =
	  vtkSmartPointer<vtkLinearExtrusionFilter>::New();
	extruder->SetInput(circle);
	extruder->SetScaleFactor(1.);
	extruder->SetExtrusionTypeToNormalExtrusion();
	extruder->SetVector(0, 0, 1);
	extruder->Update();

	// polygonal data --> image stencil:
	vtkSmartPointer<vtkPolyDataToImageStencil> pol2stenc =
	vtkSmartPointer<vtkPolyDataToImageStencil>::New();
	pol2stenc->SetTolerance(0); // important if extruder->SetVector(0, 0, 1) !!!
	pol2stenc->SetInputConnection(extruder->GetOutputPort());
	pol2stenc->SetOutputOrigin(origin);
	pol2stenc->SetOutputSpacing(spacing);
	pol2stenc->SetOutputWholeExtent(whiteImage->GetExtent());
	pol2stenc->Update();

	// cut the corresponding white image and set the background:
	vtkSmartPointer<vtkImageStencil> imgstenc =
	vtkSmartPointer<vtkImageStencil>::New();
	imgstenc->SetInput(whiteImage);
	imgstenc->SetStencil(pol2stenc->GetOutput());
	imgstenc->ReverseStencilOff();
	imgstenc->SetBackgroundValue(outval);
	imgstenc->Update();

	vtkSmartPointer<vtkMetaImageWriter> imageWriter =
	vtkSmartPointer<vtkMetaImageWriter>::New();
	imageWriter->SetFileName("labelImage.mhd");
	imageWriter->SetInput(imgstenc->GetOutput());
	imageWriter->Write();

	return 0;
};

>
> vtkPolyDataNormals
>
> just to satisfy my curiosity:
> why are you of the opinion that missing normals are a problem for that
> approach? I copied the piece of example code more or less from an old
> application I programmed some months ago; as far as I can remember, my
> input polygons did not have any normals defined, and it worked though ...
>
> regards,
> lars
>
> -------- Original-Nachricht --------
>> Datum: Mon, 12 Jul 2010 15:30:01 +0200
>> Von: "Dirk Boye" <body at nabla.org>
>> An: "Lars Friedrich Lars" <lars-friedrich at gmx.net>
>> CC: "Dirk Boye" <body at nabla.org>, vtkusers at vtk.org
>> Betreff: Re: [vtkusers] Closed vtkPolyLine to binary image
>
>> Hi Lars,
>>
>> Thank you for your help. My problem now seems to be, that my contour
>> lines
>> don't have any normals.
>>
>> Do you know if there's some function to generate the normals?
>>
>> Cheers,
>> Dirk
>>
>> > Hi,
>> >
>> > I added a small example:
>> >
>> >
>> http://www.cmake.org/Wiki/VTK/Examples/PolyData/PolyDataContourToImageData
>> >
>> > Hope that helps you.
>> >
>> > However, please read the NOTE in the description. Maybe you could fix
>> /
>> > verify the image origin problem.
>> >
>> > regards,
>> > lars
>> >
>> > -------- Original-Nachricht --------
>> >> Datum: Mon, 12 Jul 2010 08:36:32 +0200
>> >> Von: "Dirk Boye" <body at nabla.org>
>> >> An: vtkusers at vtk.org
>> >> Betreff: [vtkusers] Closed vtkPolyLine to binary image
>> >
>> >> Dear list,
>> >>
>> >> let's say I have a closed vtkPolyLine in 2D and points are
>> >> ordered clockwise and last point=first point.
>> >> The resulting Polygon is non-convex.
>> >>
>> >> I'd like to create a binary image
>> >> from that. Ones inside the line, zeros outside. See picture:
>> >> http://www.nabla.org/circlecontour.png
>> >>
>> >> Is there an filter to do that? Or do I have to check all pixels,
>> >> if they are inside?
>> >>
>> >>
>> >> Cheers,
>> >> Dirk
>> >>
>> >>
>> >>
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